Derivatization of carbon surfaces, i.e. the covalent attachment of molecules to the surface of elemental carbon, has attracted considerable interest in recent years, in particular in connection with attaching molecules to carbon nanotubes.
The derivatization of carbon may be carried out for a range of purposes which include modification of the surface properties of a carbon substrate, preparation of carbon-epoxy composites and attaching a molecule to a carbon electrode so that it can take part in an electrochemical reaction in an electrochemical sensor or an electrochemical catalyst.
Traditionally, carbon surfaces were modified by vigorous oxidation on the surface leading to the formation of carboxylic, quinonic, ketonic or hydroxylic groups, which were then reacted further with the target molecule.
A number of procedures have been described for electrochemical induced derivatization leading to the formation of a single covalent bond between a carbon electrode and a moiety which becomes attached. Examples have included electro-oxidation of primary and secondary amines described by Barbier et al J. Electrochem. Soc., vol 137, page 135 (1990), Antoniadou et al J. Appl. Electrochem., 1992, vol 22, page 1060 (1992) and Deinhammer et al Langmuir vol 10 page 1306 1994); electro-oxidation of carboxylates described by C. P. Andrieux et al, J. Am. Chem. Soc., vol 119, page 4292 (1997); and electro-reduction of diazonium salts described by P. Allongue et al J. Am. Chem. Soc., vol 119, page 201 (1997).
There have also been a number of disclosures of routes for derivatization of carbon, without electrochemistry. These include the homogeneous reduction of diazonium compounds in reducing media as described by Pandurangappa et al Analyst, vol 127, page 1568 (2002) and Leventis et al, Talanta vol 63, page 1039 (2004). Also in this category is WO2005/066618 (Schlumberger) which includes description of the diazocoupling of anthraquinonyl and nitrophenyl groups onto carbon nanotubes by means of the reduction of diazonium salts. WO2010/106404 teaches exposing the carbon to a reaction mixture in which a reactive carbene is transiently formed by reaction between a precursor and an extremely strong base.